Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 250gr | Berger Hybrid OTM bullet and 64 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon Retumbo, ReloadSwiss RS 80 and Vihtavuori N570.
Important Notice: DO NOT go below Minimum Charge or above Maximum Charge. Since we have no control over the equipment and components used, any responsibility and liability for the results achieved is rejected.
Only powders/loads that match the current filter criteria are displayed: max pressure of a load ≤ 90% of max. standardized pressure, fill rate ≥ 80% and propellant combustion ≥ 95%. Use the sliders above the tables to adjust these thresholds.
Charge: Powder weight in grains. Start with the minimum load and work up carefully.
FR (Fill Rate): Case fill as a percentage. Values above 100% mean compressed loads.
MaxP / %: Maximum chamber pressure in bar and as a percentage of the standardized maximum for this caliber.
V(0): Muzzle velocity in feet per second (fps) at the standardized barrel length.
z (Powder Burn): Estimated propellant combustion percentage at bullet exit.
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Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 88% | 54,317 psi | 85% | 2762 fps | 100% |
| Accurate High Country | <<locked>> | 86% | 56,173 psi | 88% | 2920 fps | 100% |
| Accurate MAGPRO | <<locked>> | 88% | 56,913 psi | 89% | 2927 fps | 99.7% |
| ADI AR 2209 | <<locked>> | 86% | 55,666 psi | 87% | 2848 fps | 100% |
| ADI AR 2213 | <<locked>> | 88% | 53,969 psi | 85% | 2861 fps | 99.8% |
| ADI AR 2217 | <<locked>> | 98% | 56,028 psi | 88% | 2890 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 52,417 psi | 82% | 2943 fps | 98.2% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 54,476 psi | 85% | 2913 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 56,043 psi | 88% | 2844 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 82% | 56,057 psi | 88% | 2831 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 55,434 psi | 87% | 2838 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 88% | 54,447 psi | 85% | 2858 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 90% | 56,159 psi | 88% | 2818 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 94% | 56,188 psi | 88% | 2890 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 86% | 56,695 psi | 89% | 2907 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 98% | 53,563 psi | 84% | 2927 fps | 98.3% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 49,139 psi | 77% | 2848 fps | 96.9% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 54,679 psi | 86% | 2825 fps | 98.5% |
| Bofors RP15 | <<locked>> | 92% | 57,276 psi | 90% | 2900 fps | 100% |
| Bofors RP30 | <<locked>> | 96% | 55,796 psi | 87% | 2907 fps | 100% |
| Bofors RP5 | <<locked>> | 88% | 54,447 psi | 85% | 2858 fps | 100% |
| Hodgdon H1000 | <<locked>> | 94% | 53,766 psi | 84% | 2858 fps | 100% |
| Hodgdon H4831 | <<locked>> | 88% | 56,971 psi | 89% | 2851 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 88% | 55,985 psi | 88% | 2838 fps | 99.7% |
| Hodgdon Hybrid 100V | <<locked>> | 84% | 56,260 psi | 88% | 2753 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 94% | 55,129 psi | 86% | 2976 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,695 psi | 59% | 1781 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 54,694 psi | 86% | 2769 fps | 100% |
| IMR 4831 | <<locked>> | 82% | 55,274 psi | 87% | 2769 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 88% | 57,450 psi | 90% | 2828 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 90% | 56,130 psi | 88% | 2904 fps | 99.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 49,922 psi | 78% | 2835 fps | 99.7% |
| Lovex S070 | <<locked>> | 82% | 56,869 psi | 89% | 2795 fps | 100% |
| Lovex S071 | <<locked>> | 94% | 56,014 psi | 88% | 2785 fps | 100% |
| Norma 204 | <<locked>> | 82% | 55,724 psi | 87% | 2825 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 50,778 psi | 80% | 2861 fps | 100% |
| Norma MRP | <<locked>> | 86% | 54,462 psi | 85% | 2874 fps | 100% |
| Norma URP | <<locked>> | 82% | 56,782 psi | 89% | 2808 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 57,334 psi | 90% | 2927 fps | 100% |
| Ramshot Hunter | <<locked>> | 82% | 55,695 psi | 87% | 2822 fps | 100% |
| Ramshot Magnum | <<locked>> | 92% | 55,535 psi | 87% | 2851 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,624 psi | 61% | 1824 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 82% | 57,406 psi | 90% | 2881 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 55,782 psi | 87% | 2966 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 55,143 psi | 86% | 2933 fps | 99.7% |
| Rottweil R 904 | <<locked>> | 86% | 56,391 psi | 88% | 2815 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 86% | 55,027 psi | 86% | 2828 fps | 100% |
| Shooters World SW4350 | <<locked>> | 82% | 56,869 psi | 89% | 2795 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 57,377 psi | 90% | 2749 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 54,636 psi | 86% | 2825 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 54,230 psi | 85% | 2756 fps | 99.5% |
| Somchem S365 | <<locked>> | 82% | 54,462 psi | 85% | 2762 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 55,492 psi | 87% | 2799 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 55,216 psi | 87% | 2782 fps | 100% |
| Vihtavuori N170 | <<locked>> | 94% | 54,114 psi | 85% | 2805 fps | 96.8% |
| Vihtavuori N550 | <<locked>> | 82% | 57,464 psi | 90% | 2805 fps | 100% |
| Vihtavuori N555 | <<locked>> | 86% | 54,578 psi | 86% | 2795 fps | 100% |
| Vihtavuori N560 | <<locked>> | 88% | 57,682 psi | 90% | 2933 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 92% | 54,650 psi | 86% | 2867 fps | 99.8% |
| Vihtavuori N568 | <<locked>> | 96% | 55,811 psi | 87% | 2936 fps | 99.5% |
| Vihtavuori N570 | <<locked>> | 98% | 56,913 psi | 89% | 2999 fps | 98.5% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 57,696 psi | 90% | 2749 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 90% | 55,753 psi | 87% | 2907 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 55,085 psi | 86% | 2795 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 80% | 41,684 psi | 65% | 2559 fps | 100% |
| Accurate High Country | <<locked>> | 80% | 45,571 psi | 71% | 2740 fps | 99% |
| Accurate MAGPRO | <<locked>> | 80% | 43,047 psi | 67% | 2684 fps | 97.5% |
| ADI AR 2209 | <<locked>> | 80% | 45,687 psi | 72% | 2684 fps | 99.5% |
| ADI AR 2213 | <<locked>> | 80% | 40,901 psi | 64% | 2628 fps | 98% |
| ADI AR 2217 | <<locked>> | 82% | 32,663 psi | 51% | 2434 fps | 95.5% |
| ADI AR 2218 | <<locked>> | 94% | 42,250 psi | 66% | 2733 fps | 95% |
| ADI AR 2225 | <<locked>> | 80% | 27,905 psi | 44% | 2349 fps | 96.5% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 46,079 psi | 72% | 2684 fps | 99.6% |
| Alliant Reloder-16 | <<locked>> | 80% | 52,562 psi | 82% | 2779 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 45,643 psi | 72% | 2677 fps | 99.5% |
| Alliant Reloder-22 | <<locked>> | 80% | 41,582 psi | 65% | 2635 fps | 99.1% |
| Alliant Reloder-23 | <<locked>> | 80% | 40,451 psi | 63% | 2575 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 34,896 psi | 55% | 2520 fps | 99.8% |
| Alliant Reloder-26 | <<locked>> | 80% | 45,498 psi | 71% | 2740 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 42,859 psi | 67% | 2733 fps | 95.7% |
| Alliant Reloder-50 | <<locked>> | 98% | 45,585 psi | 71% | 2782 fps | 96% |
| Baschieri & Pellagri 109 | <<locked>> | 82% | 42,612 psi | 67% | 2602 fps | 95.6% |
| Bofors RP15 | <<locked>> | 80% | 38,754 psi | 61% | 2572 fps | 98.4% |
| Bofors RP30 | <<locked>> | 80% | 32,430 psi | 51% | 2454 fps | 95.8% |
| Bofors RP5 | <<locked>> | 80% | 41,582 psi | 65% | 2635 fps | 99.1% |
| Hodgdon H1000 | <<locked>> | 80% | 33,112 psi | 52% | 2448 fps | 96.4% |
| Hodgdon H4831 | <<locked>> | 80% | 43,526 psi | 68% | 2628 fps | 98% |
| Hodgdon H4831 SC | <<locked>> | 80% | 42,757 psi | 67% | 2612 fps | 97.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 49,414 psi | 77% | 2657 fps | 100% |
| Hodgdon Retumbo | 88.2 gr | 80% | 34,011 psi | 53% | 2556 fps | 98.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,297 psi | 44% | 1591 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 51,343 psi | 80% | 2717 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 51,793 psi | 81% | 2720 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 44,701 psi | 70% | 2618 fps | 98.4% |
| IMR 7828 SSC | <<locked>> | 80% | 39,726 psi | 62% | 2612 fps | 97.8% |
| IMR 8133 Enduron | <<locked>> | 88% | 33,243 psi | 52% | 2497 fps | 95.9% |
| Lovex S070 | <<locked>> | 80% | 53,388 psi | 84% | 2746 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 35,955 psi | 56% | 2444 fps | 99.5% |
| Norma 204 | <<locked>> | 80% | 52,040 psi | 82% | 2769 fps | 99.9% |
| Norma 217 | <<locked>> | 82% | 27,325 psi | 43% | 2349 fps | 95.4% |
| Norma MRP | <<locked>> | 80% | 44,092 psi | 69% | 2703 fps | 99.9% |
| Norma URP | <<locked>> | 80% | 53,200 psi | 83% | 2759 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 39,552 psi | 62% | 2621 fps | 98.1% |
| Ramshot Hunter | <<locked>> | 80% | 52,083 psi | 82% | 2769 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 35,462 psi | 56% | 2503 fps | 98.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,935 psi | 45% | 1627 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 53,519 psi | 84% | 2828 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 33,156 psi | 52% | 2530 fps | 98.8% |
| ReloadSwiss RS 80 | 100 gr | 84% | 35,012 psi | 55% | 2552 fps | 95.1% |
| Rottweil R 904 | <<locked>> | 80% | 46,543 psi | 73% | 2654 fps | 99% |
| Rottweil R 905 | <<locked>> | 80% | 45,165 psi | 71% | 2667 fps | 99.6% |
| Shooters World SW4350 | <<locked>> | 80% | 53,388 psi | 84% | 2746 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 53,824 psi | 84% | 2700 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 44,831 psi | 70% | 2661 fps | 99.5% |
| Somchem S361 | <<locked>> | 80% | 47,442 psi | 74% | 2648 fps | 98.7% |
| Somchem S365 | <<locked>> | 80% | 50,937 psi | 80% | 2713 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 45,600 psi | 71% | 2641 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 80% | 39,842 psi | 62% | 2526 fps | 99.1% |
| Vihtavuori N170 | <<locked>> | 90% | 47,282 psi | 74% | 2690 fps | 95.1% |
| Vihtavuori N550 | <<locked>> | 80% | 53,983 psi | 85% | 2756 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 44,976 psi | 70% | 2648 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 43,874 psi | 69% | 2700 fps | 98.3% |
| Vihtavuori N565 | <<locked>> | 80% | 36,405 psi | 57% | 2526 fps | 96.4% |
| Vihtavuori N568 | <<locked>> | 84% | 36,405 psi | 57% | 2569 fps | 95% |
| Vihtavuori N570 | 103 gr | 90% | 42,656 psi | 67% | 2740 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 53,867 psi | 84% | 2700 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 38,058 psi | 60% | 2631 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 41,974 psi | 66% | 2575 fps | 99.1% |
Recommended = one of the top powders for this cartridge and bullet combination.
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 64 powders for .338-378 Weath. Mag. loaded with the .338 | 250gr | Berger Hybrid OTM. Vihtavuori N570 delivers the highest muzzle velocity at 2,999 fps; across all powders the maximum-charge window runs from 1,781 fps to 2,999 fps. ADI AR 2218 gives the best case fill at 100 %, and 64 of the 64 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 59–90 %, leaving at least 10 % headroom. The 250.0 gr projectile in 0.338" calls for a 1:11.5 twist; slower twists will usually not stabilise this weight. ADI AR 2218, ADI AR 2225, Alliant Reloder-50 reach 100 % fill or more at maximum charge, so these are compressed loads: they need a long drop tube to seat cleanly and react sensitively to the case capacity of your own brass lot. Hodgdon Retumbo, ReloadSwiss RS 80, Vihtavuori N570 rank at the top here: for .338-378 Weath. Mag. with the .338 | 250gr | Berger Hybrid OTM they combine a high case fill with complete burn and sit in the upper velocity band. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.